The present invention relates to a toilet seat attachment structure for attaching a toilet seat unit to a toilet bowl.
Nowadays, various functions, such as heating, washing and drying, are incorporated into the toilet seat unit for a western style toilet bowl. Concerning that these functions are located in a toilet seat side, the toilet seat together with a lid thereof is formed as the toilet seat unit with various functions. As an attachment structure for the toilet seat unit, the toilet bowl is materially thick and an attachment portion thereof is also thick. Further, the toilet seat unit itself may be exchanged along with a maintenance checking or the like. Therefore, in view of the operation for attaching to the toilet bowl, and attachment and detachment operations of the toilet seat unit, and in view of the fixation strength and the like due to heavy weight with many functions, it is required to improve the toilet seat attachment structure.
FIG. 17(a) shows a conventional attachment structure for a toilet seat unit. Numeral 50 designates an attachment portion including an attachment hole 50a at a toilet bowl side, and numeral 51 designates an installation plate portion including an attachment hole 51a at a toilet seat unit side. In this structure, after positioning the toilet seat unit such that the attachment hole 51a is disposed on or adjusted to the attachment hole 50a, the unit is attached by using an exclusive fastening device 52.
As shown in FIG. 17(b), the fastening device 52 is formed of a bolt 53 made of metal, an expanding member 54 having an upper flange 54a, a nut 55 made of metal and integrally disposed in the expanding member 54, and a washer 56. The expanding member 54 is a rubber molded member, and a lower side of the flange 54a constitutes a substantially cylindrical shape. Also, there is provided a plurality of larger diameter portions 54b between an upper end and a lower end of the expanding member 54, and a range L including the large diameter portions 54b is a portion in which the diameter thereof exclusively expands. In the lower end of the expanding member 54, the nut 55 is inserted at the time of molding, and integrally disposed therein. In the above described members, an axis portion of the bolt 53 is inserted into a cylinder of the expanding member 54 through the washer 56, and is engaged with the nut 55 so as to constitute the integral fastening device 52.
In the attachment operation, the fastening device 52 is inserted from the installation plate portion 51 (an upper side of the toilet bowl) into the respective attachment holes 51a and 50a, and from a condition in which the flange 54a abuts against the installation plate portion 51 like a hanging condition, the bolt 53 is rotated. Accordingly, in the expanding member 54, the nut 55 ascends around the axis portion of the bolt 53 by a rotation of the bolt 53, so that the large diameter portions 54b are compressed to expand the diameter thereof to be pressed against the inner peripheral surface of the attachment hole 50a. The installation plate portion 51 of the toilet seat unit is attached by detachably engaging the attachment portion 50 of the toilet bowl by a pressing force of the fastening device 52. In this attachment structure, since the installing operation is carried out from the upper side of the toilet bowl, as compared to a structure, for example, as disclosed in Japanese Utility Model Publication (KOKAI) No. 59-64100, in which the nut is fastened around a bolt member from the lower side of the toilet bowl, workability is better, and appearance is superior since the fastening device is pressed against the inner peripheral surface of the attachment hole.
However, the conventional structure as shown in FIGS. 17(a) and 17(b) has the following problems, and it does not sufficiently satisfy the workability of the attachment, engagement strength, reliability and the like.
Firstly, in the attachment operation, the bolt 53 is rotated to move the nut 55 upwardly until the large diameter portions 54b of the expanding member 54 are pressed against the inner peripheral surface of the attachment hole 50a by the predetermined engaging and stopping force, but it is difficult to determine when tightening of the bolt 53 is to be finished. This is because the expanding member 54 is elongate and formed of a rubber material, so that it is easy for the nut 55 to ascend freely, and it can not be determined when the final tightening point, i.e. engaging and stopping force in the design, is reached. Thus, it likely happens that the bolt is fastened too much or insufficiently.
Also, the attachment portion 50 of the toilet bowl is thick because of the restriction of a material or the like, and in correspondence thereto, the length of the expanding member 54 is extended. Thus, in case the expanding member 54 is structured such that a plurality of large diameter portions 54b is disposed between the upper end of the expanding member and the lower end thereof, and the respective large diameter portions 54b are gradually compressed from the lower side to expand the diameter thereof by moving the nut 55 upwardly, a number of rotations of the bolt 53 is naturally increased, and it can not be expected that the respective large diameter portions 54b are deformed to expand the diameter in the same condition at the same time. Namely, the large diameter portions 54b can not provide the same pressing force. Normally, after the diameter at the large diameter portion 54b adjacent to the nut 55 is initially expanded in a certain degree, the diameter of the upper large diameter portion 54b is expanded, so that a stable engaging and stopping force as a whole can not be obtained. Incidentally, in the bolt 53 made of metal, there is a problem such as a rust, and by the structure in which the nut 55 is inserted into the expanding member 54, a manufacturing cost is increased.
The present invention has been made in view of the above described problems, and an object of the invention is to provide a toilet seat attachment structure, in which workability is good even at the small space, and a toilet seat unit can be attached to a toilet bowl by strong and stable engaging and stopping force.
Further objects and advantages of the invention will be apparent from the following description of the invention.